Method and a device for gunniting converter

ABSTRACT

A method of flame gunniting a converter comprises the steps of dusting the flame with a pulverized refractory, imparting the flame the rotational movement which is relative to the longitudinal axis of the converter after the flame has been dusted with the pulverized refractory, and directing the flame tangentially to a cylindrical working surface of the converter.

United States Patent [191 Chemeris et a].

[451 Oct. 7, 1975 Inventors: Oleg Nikolaevich Chemeris, bulvar Mira, 18,kv. 69; Evgeny Vasilievich Tretyakov, ulitsa Rozy Ljuxemburg, 30, kv.32; Viktor Kirillovich Didkovsky, ulitsa Rozy Ljuxemburg, 30a, kv. 42;Vilen Davidovich Kanfer, ulitsa Tsusimskaya, 63, kv. 17, all of Donetsk;Nikolai Konstantinovich Paschenko, ulitsa Makara Mazaya, 74, kv. l,Zhdanov Donetskoi oblasti; lzmail Grigorievich Zeltser, prospektNakhimova, 154, kv. 29, Zhdanov Donetskoi oblasti; Girgory MikhailovichLjukimson, prospekt Lenina, 45, kv. l0, Zhdanov Donetskoi oblasti;Alexandr Nikolaevich Bashkatov, poselok Ukraina, pereulok Sadkovy, 70,72, Zhdanov Donetskoi oblasti; Boris Nikolaevich Melnikov, ulitsaSechenova, 68, kv. 27, Zhdanov Donetskoi oblasti; Miron YakovlevichMedzhibozhsky, perculok Nakhimova, 5, kv. 26, Zhdanov Donetskoi oblasti;llya Alexandrovich Goldberg, ulitsa Shaumiana, 47, kv. 35, Leningrad;lzrail Abramovich Juzefovsky, ulitsa Reshetova, 5, kv. 55, Leningrad;Rafail Davidovich Ratmansky, ulitsa llicha, 52, kv. 53, ZhdanovDonetskoi oblasti; Viktor Nikolaevich Irkha, ulitsa Sechenova, 68, kv48, Zhdanov Donetskoi oblasti; Jury Nikolaevich Borisov, prospektSovetskoi Armii, 16, kv. l3, Novokuznetsk Kemerovskoi oblasti; FedorFilippovich Kurochkin, prospekt Nakhimova, 154, kv. 33, ZhdanovDonetskoi oblasti, all of U.S.S.R.

22 Filed: July 3,1974

21 App]. No.: 485,598

Related US. Application Data [63] Continuation of Ser. No. 221,655, Jan.28, 1972 abandoned.

[52] US. Cl. 427/233; 118/47; 118/302; 219/121 P; 427/423; 264/270 [51]Int. CL B05B 7/20 [58] Field of Search 117/46 FS, 46 FZ, 95, 96,

117/105.2, 105.4, 93.1 PF; 118/47, 302; 264/270; 427/233, 423; 219/121 PPrimary Examiner-Michael Sofocleous Attorney, Agent, or Firm-Holman &Stern [57 ABSTRACT A method of flame gunniting a converter comprises thesteps of dusting the flame with a pulverized refractory, imparting theflame the rotational movement which is relative to the longitudinal axisof the converter after the flame has been dusted with the pulverizedrefractory, and directing the flame tangentially to a cylindricalworking surface of the converter.

1 Claim, 2 Drawing Figures US. Patent Oct. 7,1975 3,911,175

METHOD AND A DEVICE FOR GUNNITING CONVERTER This is a continuation ofapplication Scr. No. 221,655, filed Jan. 28, 1972, now abandoned.

BACKGROUND OF THE INVENTION The present invention relates to metallurgyand is intended for hot patching converter linings by gunniting orgunning.

PRIOR ART GENERALLY At present the hot patching of the converter liningsis carried out by the application of the wet gunniting process, forinstance, by pulp-spraying.

Low quality of the gunnite produced by the above method and conditionedby the need to introduce low melting-point binders and plasticizingagents into a gunnite batch; abrupt and deep cooling down of the liningsurface, to be repaired, resulting in thermal spalling of refractorymaterials; the need for the continuous heating up of the placed gunniteto produce ceramic bonds between the grains of a highly refractoryconstituent of the gunnite; inadequate sticking to tar concrete(tar-dolomite refractories) these and a series of other disadvantages donot enable the wet gunniting procedures to be effectively used for thehot patching of the converter lining.

A method of gunniting the converter lining with the aid of a fuel-oxygentorch shooting a pulverized refractory fed into its flame is widelyknown.

With the flame gunniting method, the above disadvantages are practicallycompletely avoided. As to the quality aspects of the gunnite, it rankswith the best types of highly-refractory burned articles: up to 3%porosity is provided and a structure featuring a large number of directbonds; the gunnite produced becomes self-supporting during the gunnitinginterval; no thermal shock is encountered and depositing to tar concreteis quite adequate.

However in gunniting with a uniflow flame (the flame directed at rightangle to a working surface of the lining, being gunnited) peculiar tothe flame gunniting process is low gunning efficiency or low yield(gunning efficiency is a weight ratio of a gunnite built-up to thelining zone under repair to that of a refractory gunnite constituent fedto a repair zone). In that case, the gunning efficiency or yield isusually equal to -20% but not in excess of 40%.

It is an object of the present invention to develop a method forgunniting converter linings and a device for doing the same, which wouldsubstantially increase efficiency of gunniting, enable the production ofa slagand heat-resistant gunnite containing basic refractories, tarconcretes among them, avoid the loss of usable time in gunnite burningand preclude the possibility of thermal spalling of the refractorylining during repairs.

According to the specified and other objects in a method of gunniting aconverter lining with a flame dusted with a pulverized refractory,conforming to this invention, the flame is directed tangentially to thelining surface, and imparted a rotary motion relative to a longitudinalaxis of the converter.

In order to place the above method into effect a device has beendeveloped comprising pipes or ducts arranged concentrically relative toeach other and intended for feeding onto a converter lining a pulverizedrefractory, fuel and oxygen to be issued from a nozzle whose axis is atright angle to that of the pipe lines with the latter being deflected,conforming to the present invention, from the longitudinal axis at al5-90 angle in a plane perpendicular to the nozzle axis.

BRIEF DESCRIPTION OF THE DRAWINGS In order to make the nature of thepresent invention more fully apparent an exemplary embodiment of theproposed device is described below, which is to be considered with duereference to the accompanying drawings, in which:

FIG. 1 shows a converter and a gunniting device, conforming to thisinvention; and

FIG. 2 gives a cross-sectional view of ducts of a converter gunnitingdevice.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A device for the flamegunniting of converter linings is a tuyere hereinafter referred to aslance 1, attached mechanically on manipulator 2 mounted on selfpropelledtruck 3. The opposite side manipulator 2 is connected to header 4, whichencloses flexible metal pipes 5, 6 and 7 whose purpose is to supply tolance 1 respectively a mixture of a pulverized refractory with the fueland oxygen and to feed and drain water which serves for cooling lance 1.

Self-propelled truck 3 is designed for handling both manipulator 2 andlance I over a shop working floor and for imparting to lance 1 areciprocating motion in the course of gunniting. The manipulator allowsfixing lance 1 in a preset position in the converter interior impartingit during the gunniting operation, if necessary, a rotary motion over ageneratrix of a cone, altering simultaneously its angle of inclinationrelative to its axis of rotation.

Lance 1 consists of nozzle 8 and four ducts 9 arranged concentricallyand intended for supplying nozzle 8 with the mixture of the pulverizedrefractory with fuel and oxygen and water.

The refractory powder-fuel mixture is fed along central duct 10 (FIG. 2)while the second duct 11 is employed for feeding the oxygen underpressure. The third and fourth ducts l2 and 13 serve to supply and drainhigh-pressure water.

Maximum diameter of the external lance duct is mm with the minimumdiameter amounting to 108 mm. An axis of lance nozzle 8 is directed atright angle to the ducts, the latter being deflected from a longitudinalaxis at an angle of 15-90 in a plane perpendicular to the nozzle axis.

For continuous gunniting, the axis of nozzle 8 must be tangential inrelation to a cylindrical surface of the lining of converter 14 (in FIG.1 the working surface of the converter lining is shown by a dot-and-dashline) with nozzle 8 disposed in the immediate vicinity of the liningsurface.

Construction of lance 1 with nozzle 8 perpendicular to the axis of ducts9 makes it possible to shoot the flows of the pulverized refractorymixed with the fuel and oxygen against the lining of the convertercylindrical part, i.e., against lining sections exposed to the mostintensive wear. However, due to a taper of a converter mouth straightducts 9 it is impractical to make the location of nozzle 8 near thesurface of the cylindrical portion of the lining in a zone adjacent to abutt joint with the converter mouth or near the surface of the convertermouth lining. Deflection of ducts 9 in a plane perpendicular to thenozzle axis at an angle of l5-90, which is close to a taper of theconverter 14 mouth, tends to eliminate the above disadvantage inherentin lances with straight-line ducts. However, duct deflection must bereduced to a minimum, as an increase in an angle of bending of the ductsresults in a substantial growth in duct weight and hence the weight ofthe lance, as a whole; in addition the resistance encountered by therefractory powderfuel mixture on its way to the lance is also liable toincrease. With ducts 9 deflected at an angle more than 90 seriousdifficulties can arise in introducing the device into the converterinterior prior to gunniting and in removing it when the process iscompleted. That is why maximum deflection of the ducts must not exceed90.

At present the device and the method of the flame gunniting ofconverters is employed for hot patching tar concrete lining of l30-toncapacity oxygen converters. The working part of lance l is 7,500 mmlong, with its external diameter being equal to 108 mm. Ducts 9 of lance1 are bended in two planes at right angle to each other: at a 90 angleat the nozzle and at 20 when spaced at a distance of 3,000 mm from thenozzle. By using the above nozzle, up to 200 kg/min of the mixturecontaining the pulverized refractory and the fuel and up to 60cub.m.lmin. of oxygen can be supplied to the converter lining.

The device functions as follows:

Upon tapping both the metal and the slag at a temperature of a workingsurface of a converter lining ranging from 1,350 to l,500C, lance 1 isintroduced into converter 14 (FIG. 1) so that an axis of a straightlineportion of lance 1 coincides with a longitudinal converter axis. In thatcase, nozzle 8 of lance 1 is always tangential to the working surface ofconverter 14 lining. Depending on the nature of hot patching, nozzle 8is spaced at a different distance apart from working surface of thelining: at a distance of up to 0.1 of the radius of converter 14, incontinuous gunniting, and up to 0.1 0.3 of a converter radius ingunniting lining sections subjected to local wear.

For flame gunniting, the converter linings depending on the nature ofrepairs and type of the refractory being deposited, use may be made ofdifferent refractory materials mixed with solid pulverized fuel. Thus,in the continuous gunniting of a tar concrete lining, a finely divided(with grain size less than 0.1 mm) mix is utilized consisting of twocomponents: powdered magnesite 6070% and pulverized coke 3O 40%.

To initiate the gunniting process, the supply of the pulverizedrefractory-fuel mixture and the oxygen supply are simultaneously turnedon. The fuel issuing from nozzle 8 mixes with the oxygen, ignites andburns out forming wild high-temperature flame 15. On account oftangential position of the nozzle relative to the working surface ofconverter 14, outflow of the streams containing the mixture of thepulverized refractory with the fuel and the oxygen, flame l5 and fluegases are imparted a rotary in relation to the longitudinal axis ofconverter 14 motion within the cylindrical cavity of converter 14 (thedirection of rotation of flame 15 is indicated with arrows in FIG. 1) Ina cross-sectional view of converter 14, the path of rotating gases lookslike a series of concentric closed circles. On hitting the lining,particles of the pulverized refractory move over its working surface andon being heated to a plastifying temperature stick to it. Crosshatchedsections in FIG. 1 show gunnite 16 in cross-section, built-up to thelining. The particles rebounded from the lining surface are entrained bya flow of rotating gases, driven back to the lining under the action ofcentrifugal force arising on account of different densities ofhightemperature gases and, on establishing again a contact with theworking surface of the lining, stick to it in a more remote region.

With lance l fixed stationary in the coarse of gunniting, the thicknessof a built-up being deposited varies with both the diameter and heightof converter 14. Maximum buildup is exhibited in the primary annularzone at the point the flame mates with the converter lining. As aminimum spacing between nozzle 8 and the working surface of the liningincreases, the building-up thickness tends also to increase in theprimary zone. However when the minimum distance between nozzle 8 and thelining working surface exceeds 0.3 of an internal radius of converter14, intensity of rotation of flame l5 dusted with the pulverizedrefractory decreases abruptly with the quality of combustiondeteriorating also. This results in a substantial carry away of thepulverized refractory and in a lower gunnite qual ity. That is why ingunniting lining zones subjected to local wear nozzle 8 must be locatedat a distance of not over than 0.3 of the converter internal radius fromthe working surface of the lining. In continuous gunniting, nozzle 8 isimparted, with the aid of manipulator 2, a rotary motion in relation toa longitudinal axis of converter l4, and with the aid of self-propelledtruck 3, an intermitent reciprocating movement. Maximum gunnite build-upis progressively displaced at both along the diameter and the height ofconverter 14 which allows production of a uniform in thickness gunnitethroughout the worn converter lining.

The proposed invention ensures high technical and economicalcharacteristics, which have been proved by long-term trials of themethod of the invention both of experimental tigs and on aproduction-scale. In the course of mastering the proposed method anddevice for the flame gunniting of converter linings, an increase inlining service life has been achieved: by heats in gunniting tarconcrete refractories and by 50 heats in gunniting magnesiterefractories in a constant lining layer. Specific consumption of thepulverized refractory-fuel mixture per 1 ton of steel melted during theoperating period of a gunnited converter was equal respectively to 0.8kg/ton and 1.6 kg/ton. Converter downtime per each gunniting operationwas 25 min. with the consumption of the pulverized refractory-fuelmixture equalling 5 tons at the above interval.

Flame gunniting by the application of the above method makes it possibleto reliably and effectively smear lining zones subjected to localburnout at the end of a campaign and to preclude practically completelypremature shutdown of a unit for lining replacement. This will allowplanning a month schedule of cold repairs in a converter shop dependingon maximum lining surface of a converter;

the relative rotation between the cylindrical working surface of theconverter and the angle of the flame substantially tangent thereto andcontinuously flame spraying gunnite in a path of rotating gases so thatthe plastified material adheres to the cylindrical surface and portionsof the material which rebound from the cylindrical working surface aredriven back onto the cylindrical surface under centrifugal forces of theflue gases of the

1. A METHOD OF FLAME SPRAYING GUNNITE ON THE INTERIOR CYLINDRICALSURFACE OF A CONVERTER, SAID METHOD COMPRISING THE STEPS OF: A.PROVIDING AN INTERIOR CYLINDRICAL WORKING SURFACE OF A CONVERTER, B.DUSTING A FLAME WITH A PULVERIZED REFRACTORY TO PROVIDE A PLASTIFIEDMATERIAL TO BE COATEDONTO THE INTERIOR CYLINDRICAL WORKING SURFACE, C.IMPARTING TO THE FLAME CONTAINING THE PLASTIFIED MATERIAL A ROTATIONALMOVEMENT RELATIVE TO THE LONGITUDINAL AXIS OF THE CYLINDRICAL SURFACE OFTHE CONVERTER AFTER THE FLAME HAS BEEN DUSTED WITH THE PULVERIZEDREFRACTORY, AND D. DIRECTING THE TANGENTIALLY WITH THE PLASTIFIEDMATERIAL ENTRAINED THEREIN TO THE INTERIOR CYLINDRICAL WORKING SURFACEOF THE CONVERTER BY CONTROLLING THE RELATIVE ROTATION BETWEEN THECYLINDRICAL WORKING SURFACE OF THE CONVERTER AND THE ANGLE OF THE FLAMESUBSTANTIALLY TANGENT THERETO AND CONTINUOUSLY FLAME SPRAYING GUNNITE INA PATH OF ROTATING GASES SO THAT THE PLASTIFIED MATERIAL ADHERES TO THECYLINDRICAL SURFACE AND PORTIONS OF THE MATERIAL WHICH REBOUND FROM THECYLINDRICAL WORKING SURFACE ARE DRIVEN BACK ONTO THE CYLINDRICAL SURFACEUNDER CENTRIFUGAL FORCES OF THE FLUE GASES OF THE FLAME.